1. Field of the Invention
This invention pertains to the field of energy dispersive X-ray fluorescence analysis, and in particular to the processing of data collected by a scanning (and/or transmission) electron microscope (SEM, STEM) and the presentation and storage of the data for meaningful analysis and use both on-line and off-line. Specifically, the apparatus embraces a ratemeter which gives a voltage output proportional to the intensity of the energy window or windows under consideration and additionally an output which is an absolute digital representation of the intensity count rate. The invention includes a new method of dead time correction to enable meaningful single channel intensity data to be handled. The invention further includes input multiplexing and multiple output voltage buffering of the ratemeter to accommodate multiple single channel signals. Furthermore, an extension of the ratemeter is disclosed to enable its use in conjunction with X-ray mapping, thereby permitting enhancements to be made on mapping single channel analyzer data. This enhancement is created by inhibiting single channel analyzer data by using preset values of the intensity count rate of either the channel itself or of other independent single channel analyzer outputs. The invention further includes a new method of storing multiple line scans of multiple single channel analyzer outputs in a multichannel analyzer in a multichannel scaling mode involving signal averaging technique circuits. It further includes a new method of content mapping, a method of processing stored line scans of a scanning electron microscope and means for displaying processed unprocessed stored multiple line scans on the display of a multichannel analyzer and means of displaying processed or unprocessed stored multiple line scans on the display of a scanning electron microscope.
2. Description of the Prior Art
The history of energy dispersive X-ray fluorescent spectrometers is summarized in an article entitled "A Comparison of Wavelength Dispersive and Energy Dispersive X-ray Fluorescent Analysis" by R. Jenkins published in the Edax Editor, Vol. 8, No. 2, April 1978. Among prior art devices to which the invention pertains is the model 711 X-ray energy analyzer manufactured by Edax International Inc., Prairie View, Illinois. This invention specifically will be embodied in the Edax model 9100 series energy dispersive X-ray analysis systems also manufactured by Edax International, Prairie View, Illinois.